Gene products, e.g., neuropeptides and small peptide hormones, are often synthesized as part of a larger inactive polyprotein precursor. To generate a bioactive or processed molecule, a precursor can undergo one or several posttranslational modifications. These modifications can include glycosylation, cleavage, phosphorylation, amidation, and acetylation. The processing events can occur in different organelles during intracellular transport. Peptides can then be sorted in secretory granules until an extracellular signal triggers secretion. In order for the peptide to be secreted in active form, the peptide has to be properly processed in the cell including cleavage of the precursor sequences.